We have deliberated on the information you have provided. From the reading which we have done on the subject, we understand that Black Hat SEO are essentially advertising methods. They are considered unethical by a large number of internet programmers and search indexing websites like Google Inc. consider them against their Terms of Condition.

That being said, we were not able to come across any piece of legislation that would incriminate this mode of advertisement as an action which would be illegal. Google Inc. is but one website that indexes the websites and then ranks them as appropriate or inappropriate as per its Terms of Conditions. If a website enters in a contract with Google and then violates the terms, the income of the website will become haram, but if a website does not enters into any contract yet is monitored and ranked by Google, then the website has not committed any illegal act, and the income will be permissible.

We have come across a few actual court cases where Google de-listed websites for using Black Hat SEO, reducing the traffic to those websites by more than 50%. The websites sued Google for this in the court, but their claims were dismissed. The underlying reason for the court opting for Google’s opinion over the plaintiffs was that Google has the liberty to allow and disallow the websites from advertising on its own. Hence, the Black Hat SEO violated Google’s terms and not that of any law.[1]

However, the issue will remain that Black Hat SEO methods are unethical. They have an element of deception in them. They may also be detrimental to one’s website and business should Google or other such search engines choose to de-list the website or de-rank it. In light of this, it will be undesirable to use these methods, but not illegal. According to Shariah while these marketing ploys may not be outright haram, they are definitely discouraged. The deliberate use of such tactics will make one’s business void of barakah (blessings) and hence should be avoided.

Although we recommend you not to use these methods in your internet marketing business for your client, at the same time the income generated from the work in Black Hat SEO will be permissible and halal.